An Efficient Approach for Quantifying the Mechanical Degradation of Ni‐Rich NMC‐based Cathodes for Lithium‐Ion Batteries using Nano‐XCT Analysis

Abstract

AbstractLiNi0.8Co0.1Mn0.1O2 has emerged as a promising electrode material for automotive lithium‐ion batteries due to its high specific discharge capacity, cost‐effectiveness, and reduced cobalt content. However, despite all mentioned beneficial attributes, the widespread adoption of this material class is impeded by active material degradation during cycling operation, which is linked to performance loss. This study compares scanning electron microscopy images and nano X‐ray computed tomography scans with a 3D reconstruction of pristine and cycle‐aged battery electrodes to determine structural changes over cycle life. Although a very moderate current rate was chosen for the cycle test, which suggests a homogeneous load across the entire electrode, particle fracture varied across electrode thickness and particle size. A quantitative analysis of the active material‘s gray scale value distribution reveals severe degradation near the separator interface with a reciprocal relationship to particle radius. Remarkably, particle shape and size remain relatively unchanged despite cracking, eliminating the need to adjust these parameters in aging simulations. Moreover, it underscores the practical significance of particle cracking, as it can significantly impact the electrode‘s performance. Thus, analyzing changes in particle shape and size alone is insufficient, and a comprehensive exploration of the particle interior using nano‐XCT is necessary.